Biology subjects

Killinger, B.

Publications and source records attributed to Killinger, B..

4 recordsLinked to original sources

bioRxiv2025

Alpha-synuclein phosphorylation is abundant in the non-synucleinopathy human brain

Phosphorylation of alpha-synuclein (syn) at serine 129 (PS129) marks aggregates in synucleinopathies but also occurs physiologically, potentially signaling protein interactions during neuronal activity. Technical barriers, including postmortem dephosphorylation, have hindered the study of physiological PS129 in the human brain. Using biotinylation by antibody recognition (BAR) on surgically resected temporal lobectomy tissues (without post-mortem interval), we mapped physiological PS129 and total syn interactomes. BAR identified 1,095 interactions with 513 syn-specific, 524 shared, and 58 PS129-specific, mostly associated with vesicles at presynaptic nerve terminals. PS129-specific interactions were uniquely associated with postsynaptic density proteins SHANK1/3, DLGAP1-4, DLGAP1-3, and DLG2-4, as well as nuclear-associated proteins HUWE1, HNRNPM, RBM14, ITCH, OGT, PHF24, and PPP2R5E. Fluorescent staining confirmed physiological PS129 proximal to dendrites and within the nucleus. Confirmation in healthy cynomolgus macaques (62% syn and 41% PS129 overlap) demonstrated that the interactomes were physiological rather than disease- or aggregate-associated. We conclude that physiological PS129 plays a unique and underappreciated role in postsynaptic neurons extending from the postsynaptic active zone to the nucleus. These interactomes benchmark normal syn biology, illuminating the transition to synucleinopathy pathology. Significance StatementDisease-associated syn phosphorylation (PS129) was recently identified in healthy mammalian brain and may signal syn-protein interactions during neuronal activity. Here, we surmounted technical hurdles and characterized syn and PS129 interactomes directly in the human brain. Results showed a unique significance for PS129 in post-synaptic active zones and nuclear compartments, which was confirmed in healthy non-human primates. These syn interactomes will be a valuable reference for understanding synucleinopathy mechanisms in the context of normal syn biology.

neuroscience↗

bioRxiv2023

Neither alpha-synuclein-preformed fibrils derived from patients with GBA1 mutations nor the host murine genotype significantly influence seeding efficacy in the mouse olfactory bulb.

Parkinsons disease (PD) is a neurodegenerative disease characterized by progressive motor symptoms and alpha-synuclein (syn) aggregation in the nervous system. For unclear reasons, PD patients with certain GBA mutations (GBA-PD) have a more aggressive clinical progression. Two testable hypotheses that can potentially account for this phenomenon are that GBA1 mutations promote syn spread or drive the generation of highly pathogenic syn polymorphs (i.e., strains). We tested these hypotheses by treating homozygous GBA1 D409V knockin (KI) mice with human -syn-preformed fibrils (PFFs) and treating wild-type mice (WT) with several syn-PFF polymorphs amplified from brain autopsy samples collected from patients with idiopathic PD and GBA-PD patients with either homozygous or heterozygous GBA1 mutations. Robust phosphorylated-syn (PSER129) positive pathology was observed at the injection site (i.e., the olfactory bulb granular layer) and throughout the brain six months following PFF injection. The PFF seeding efficiency and degree of spread were similar regardless of the mouse genotype or PFF polymorphs. We found that PFFs amplified from the human brain, regardless of patient genotype, were generally more effective seeders than wholly synthetic PFFs (i.e., non-amplified); however, PFF concentration differed between these two studies, and this might also account for the observed differences. To investigate whether the molecular composition of pathology differed between different seeding conditions, we permed Biotinylation by Antibody Recognition on PSER129 (BAR-PSER129). We found that for BAR-PSER129, the endogenous PSER129 pool dominated identified interactions, and thus, very few potential interactions were explicitly identified for seeded pathology. However, we found Dctn2 interaction was shared across all PFF conditions, and Nckap1 and Ap3b2 were unique to PFFs amplified from GBA-PD brains of heterozygous mutation carriers. In conclusion, both the genotype and syn strain had little effect on overall seeding efficacy and global PSER129-interactions.

neuroscience↗

bioRxiv2019

Epigenomic analysis of Parkinson’s disease neurons identifies Tet2 loss as neuroprotective

PD pathogenesis may involve the epigenetic control of enhancers that modify neuronal functions. Here, we comprehensively profile DNA methylation at enhancers, genome-wide, in neurons of 57 PD patients and 48 control individuals. We found a widespread increase in cytosine modifications at enhancers in PD neurons, which is partly explained by elevated hydroxymethylation levels. Epigenetic dysregulation of enhancers in PD converge on transcriptional abnormalities affecting neuronal signaling and immune activation pathways. In particular, PD patients exhibit an epigenetic and transcriptional upregulation of TET2, a master-regulator of cytosine modification status. TET2 inactivation in a neuronal cell line results in cytosine modification changes that are reciprocal to those observed in PD neurons. Furthermore, Tet2 inactivation in mice fully prevents dopaminergic neuronal loss in the substantia nigra induced by prior inflammation. Tet2 loss in mice also attenuates transcriptional immune responses to an inflammatory trigger. Thus, widespread epigenetic dysregulation of enhancers in PD neurons may, in part, be mediated by increased TET2 expression. Decreased Tet2 activity is neuroprotective, in vivo, and may be a novel therapeutic target for PD.

neuroscience↗

bioRxiv2018

Differential DNA modification of an enhancer at the IGF2 locus affects dopamine synthesis in patients with major psychosis

Dopamine dysregulation is central to the pathogenesis of diseases with major psychosis, but its molecular origins are unclear. In an epigenome-wide investigation in neurons, individuals with schizophrenia and bipolar disorder showed reduced DNA modifications at an enhancer in IGF2, which disrupted the regulation of the dopamine synthesis enzyme tyrosine hydroxylase and striatal dopamine levels in transgenic mice. Epigenetic control of this enhancer may be an important molecular determinant of psychosis.

neuroscience↗